Direct Measurement of the Electrical Abruptness of a Nanowire p–n Junction

Electrostatic potential maps of GaAs
nanowire, p–n junctions have been measured via off-axis electron
holography and compared to results from in situ electrical probing,
and secondary electron emission microscopy using scanning electron
microscopy. The built-in potential and depletion length of an axial
junction was found to be 1.5 ± 0.1 V and 74 ± 9 nm, respectively,
to be compared with 1.53 V and 64 nm of an abrupt junction of the
same end point carrier concentrations. Associated with the switch
from Te to Zn dopant precursor was a reduction in GaAs nanowire diameter
3 ± 1 nm that occurred prior to the junction center (n = p) and
was followed by a rapid increase in Zn doping. The delay in Zn incorporation
is attributed to the time required for Zn to equilibrate within the
Au catalyst.